Finding breast cancer early greatly improves a woman's chances for survival from the disease. Early detection also conserves health-care system resources. A high-quality mammogram and a clinical breast exam done by a doctor are the most effective approaches for early detection.
A mammogram is a low-dose X-ray of the breasts to look for abnormal changes. The results are recorded on film or directly into a computer for a radiologist to read for abnormalities. Breast cancer can be found through a screening mammogram or, in situations in which abnormalities have already been observed, a diagnostic mammogram.
A mammogram is obtained using a mammography unit, such as mammography unit 100 depicted in FIG. 1. The unit includes stand 118, as well as image-acquisition elements, such as an X-ray source, shown generally at 102, collimator 104, compression plate 106, and cassette holder 110.
Collimator 104 restricts the size and shape of the X-ray beam generated by X-ray source 102. Cassette holder 110 houses a removable cassette (not depicted) that includes an image receptor, such as film. The cassette is inserted into holder 110 before each image is taken by mammography unit 100 and is removed thereafter. The film is developed to produce a radiographic image of the breast. Cassette holder 110 has a flat, beam-facing surface or imaging area 112, which is transparent to X-rays. Also in cassette holder 110 is an anti-scatter grid assembly.
Compression plate 106, which comprises a thin, X-ray transparent material, is used to compress the breast to a near uniform thickness against imaging area 112. Adjustment system 108 enables compression plate 106 to be adjusted to provide the requisite amount of compression.
The image-acquisition elements are rotatably coupled to stand 118 via pivot element 114 and coupler 116. The coupler is movable along guide-ways 120 to collectively alter the height of the image-acquisition elements. Pivot element 114 permits the image-acquisition elements to partially collectively rotate in the direction shown with respect to stand 118. This arrangement provides for two projective viewpoints. In particular, the orientation depicted in FIG. 1 provides a head-to-foot or “craniocaudal” (CC) view. In the craniocaudal view, the breast is compressed horizontally and the X-ray is taken in the direction from head to toe. Partial rotation about pivot element 114 from the orientation shown in FIG. 1 provides a mediolateral oblique (MLO) view, wherein the breast is compressed vertically and the X-ray is taken from the side of the breast.
FIG. 2 depicts a simplified view of relevant portions of unit 100 during a mammography. A patient's breast 222 is positioned on the imaging area 112 (FIG. 1) of cassette holder 110 by a radiologic technologist. To image the breast fully, as much of the breast as possible must be positioned between cassette holder 110 and plate 106. Specifically, it is important to capture as much of the “tail” region 226 of the breast as possible between the holder and plate so that it can be radiographically imaged. To accomplish this, the patient is asked to lean forward, which brings the patient's chest wall 224 into tight contact with the rigid forward surfaces and edges of cassette holder 110 and plate 106. Adjustment system 108 enables compression plate 106 to be moved (downward) against the breast, so that the breast is compressed between the compression plate and cassette holder 110.
Compression of the breast can be quite painful for the patient. Furthermore, contact of the chest wall (especially near the axilla) with the edges of compression plate as it is lowered can be an additional source of pain. But compression is essential because it: (1) provides a more uniform thickness of breast tissue, thereby increasing image quality by reducing the thickness of tissue that x-rays must penetrate, (2) spreads out the tissue so that small abnormalities are less likely to be obscured by overlying breast tissue, (3) decreases the amount of scattered radiation, wherein scatter degrades image quality, (4) reduces the required radiation dose since a thinner amount of tissue is being imaged, and (5) immobilizes the breast thereby preventing motion blur.
With continuing reference to FIGS. 1 and 2, X-ray source 102 produces X-ray beam 220. The X-ray beam is passed through collimator 104, which restricts the size and shape of beam 220. The X-ray beam passes through compression plate 106 and through breast 222. A radiological image of the breast is captured on film that is in cassette holder 110.
FIG. 2 depicts a CC view being obtained from the mammography unit. As previously discussed, a MLO view will also be obtained, wherein the image-acquisition elements are rotated about pivot element 114. If the mammography is diagnostic, rather than for screening, additional views may be taken as well.
Notwithstanding its utility for early detection of cancer, many women display an aversion to mammography. Even though the National Cancer Institute recommends that women aged 40 and older should have a screening mammogram every 1-2 years, only 71.8% of women between the ages of 50 and 64 and 72.5% of women ages 65-74 had received a mammogram within the previous 2 years according to 2005 government figures.
There are several reasons why women do not routinely undergo mammography. One reason is cost; those without healthcare coverage are less likely to pay out-of-pocket or seek assistance. An NEJM study found that even a small co-pay of $12 deterred 11% of women from having a mammography. The study also identified time constraints, the cost of transportation, and lost wages as contributing to a lack of screening. A number of hospitals, cancer centers and other healthcare groups have started mobile mammography vans to bring affordable, accessible and convenient mammograms to their communities. Many offer free or low-cost mammograms to women who are uninsured and/or cannot afford a mammogram.
But there are other factors that dissuade women from undergoing a mammogram. A Kaiser Permanente Study published in 2011 cited pain, embarrassment and time as factors that deterred women having health insurance from undergoing screening. As previously mentioned, both breast compression and the accompanying rubbing/pinching of the skin are unpleasant. And with regard to embarrassment, the patient will normally be bare-chested for the mammogram.
There have been attempts in the prior art to address the issue of pain and discomfort with cushioning strips and gel pads that are used in conjunction with the mammography unit. A need remains, however, for a way to decrease the discomfort that accompanies a mammogram and to do it in a way that maintains patient dignity and does not add significantly to the cost of the mammogram unit or the procedure.